Method and apparatus for transmitting M2M ranging information in a wireless communication system

ABSTRACT

A method for transmitting Machine to Machine (M2M) ranging information in a wireless communication system is disclosed. The method includes transmitting an Uplink Channel Descriptor (UCD) including an M2M ranging region Type/Length/Value (TLV). When the UCD is transmitted, a ranging region TLV identifying the same region as the M2M ranging region TLV is included in the UCD.

TECHNICAL FIELD

The present invention relates to wireless communications, and moreparticularly, to a method and apparatus for transmitting ranginginformation related to a Machine to Machine (M2M) device in a wirelesscommunication system.

BACKGROUND ART

Legacy communication is mostly Human to Human (H2H) communicationconducted via a Base Station (BS). Now, the development of communicationtechnology enables M2M communication. As its appellation implies, M2Mcommunication is communication between electronic terminals. While M2Mcommunication means wired or wireless communication between electronicterminals or communication between a human-controlled terminal and amachine in its broadest sense, it is typical in these days that M2Mcommunication refers to wireless communication between electronicterminals, i.e. terminals.

When the concept of M2M communication was introduced in the early 1990s,it was regarded merely as the concept of remote control or telematicsand its market was very limited. However, M2M communication has beendrastically developed and the M2M communication market has attractedmuch attention all over the world including Korea over the past fewyears. Especially, M2M communication has a great influence on the fieldsof fleet management, remote monitoring of machines and facilities, smartmetering for automatically measuring the working time of constructionequipment and the consumption of heat or electricity, etc. in the marketof Point Of Sales (POS) and security-related applications. It isexpected that M2M communication will find its various uses inconjunction with legacy mobile communication, very high-speed wirelessInternet or Wireless Fidelity (WiFi), and low-output communicationsolutions such as Zigbee and thus will extend to Business to Customer(B2C) markets beyond Business to Business (B2B) markets.

In the era of M2M communication, every machine equipped with aSubscriber Identity Module (SIM) card can be managed and controlledremotely because it is possible to transmit data to and receive datafrom the machine. For example, M2M communication is applicable to a verybroad range including numerous terminals and equipment such as a car, atruck, a train, a container, an automatic vending machine, a gas tank,etc.

As the application types of M2M devices have been increasing in number,a number of such M2M devices may exist in the same BS. When a hugenumber of M2M devices in idle state attempt network reentry, connectioncollisions and congestions increase, thus degrading communicationperformance. However, there is no specified procedure for performingnetwork reentry in idle state by an M2M device having differentcharacteristics from an existing terminal (H2H terminal).

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ona method and apparatus for transmitting information about a Machine toMachine (M2M) ranging region in a wireless communication system.

It will be appreciated by persons skilled in the art that the objectsthat could be achieved with the present invention are not limited towhat has been particularly described hereinabove and the above and otherobjects that the present invention could achieve will be more clearlyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings.

Technical Solution

The object of the present invention can be achieved by providing amethod for transmitting M2M ranging information at a Base Station (BS)in a wireless communication system, including transmitting an UplinkChannel Descriptor (UCD) including an M2M ranging regionType/Length/Value (TLV). When the BS transmits the UCD, the BS includesa ranging region TLV identifying the same region as the M2M rangingregion TLV in the UCD.

In another aspect of the present invention, provided herein is a methodfor receiving M2M ranging information at an M2M device in a wirelesscommunication system, including receiving a UCD including an M2M rangingregion TLV. The UCD includes a ranging region TLV identifying the sameregion as the M2M ranging region TLV.

In another aspect of the present invention, provided herein is a BS fortransmitting M2M ranging information in a wireless communication system,including a Radio Frequency (RF) unit and a processor. The processorcontrols transmission of a UCD including an M2M ranging region TLVthrough the RF unit, and when the UCD is transmitted, the processorincludes a ranging region TLV identifying the same region as the M2Mranging region TLV in the UCD.

In a further aspect of the present invention, provided herein is an M2Mdevice for receiving M2M ranging information in a wireless communicationsystem, including an RF unit and a processor. The processor receives aUCD including an M2M ranging region TLV through the RF unit, and the UCDincludes a ranging region TLV identifying the same region as the M2Mranging region TLV.

The above four technical aspects of the present invention may includeall or a part of the followings.

A dedicated ranging indicator may be set to 1 in the ranging region TLVof the UCD.

An M2M ranging region specified by the M2M ranging region TLV may beindicated by an Orthogonal Frequency Division Multiple Access (OFDMA)symbol offset, a subchannel offset, the number of OFDMA symbols, and thenumber of subchannels.

A ranging region specified by the ranging region TLV may be indicated byan OFDMA symbol offset, a subchannel offset, the number of OFDMAsymbols, and the number of subchannels.

If the BS does not include dedicated ranging information in a pagingmessage, a User Equipment (UE) may neglect the ranging region TLV.

A ranging region specified by the M2M ranging region TLV may be used foran M2M device to transmit a ranging code.

Advantageous Effects

According to the embodiments of the present invention, information aboutan M2M ranging region can be transmitted in a manner that minimizeseffects on legacy terminals (H2H terminals) in a wireless communicationsystem.

It will be appreciated by persons skilled in the art that that theeffects that could be achieved with the present invention are notlimited to what has been particularly described hereinabove and otheradvantages of the present invention will be more clearly understood fromthe following detailed description taken in conjunction with theaccompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 illustrates a Time Division Duplexing (TDD) frame in anOrthogonal Frequency Division Multiple Access (OFDMA) physical layer;

FIG. 2 illustrates a data region for defining OFDMA resource allocation;

FIG. 3 illustrates an OFDMA data region in an Uplink (UL) zone of aframe;

FIG. 4 is a flowchart illustrating an initialization procedure of a UserEquipment (UE);

FIG. 5 is a diagram illustrating a signal flow for a ranging procedure;

FIG. 6 illustrates an exemplary allocation of a Machine to Machine (M2M)ranging region;

FIG. 7 illustrates allocation of an M2M ranging region according to anembodiment of the present invention;

FIG. 8 illustrates allocation of an M2M ranging region according toanother embodiment of the present invention; and

FIG. 9 is a block diagram of an M2M device and a Base Station (BS)according to an embodiment of the present invention.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention with reference to the accompanying drawings. Thedetailed description, which will be given below with reference to theaccompanying drawings, is intended to explain exemplary embodiments ofthe present invention, rather than to show the only embodiments that canbe implemented according to the invention.

The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details. For example, thefollowing detailed description is given under the assumption that anInstitute of Electrical and Electronics Engineers (IEEE) 802.16 systemis being used as a wireless communication system. However, thedescription is applicable to any other wireless communication system(e.g. Long Term Evolution (LTE)/LTE-Advanced (LTE-A)) except forspecific features inherent to the IEEE 802.16 standards.

In some instances, known structures and devices are omitted or are shownin block diagram form, focusing on important features of the structuresand devices, so as not to obscure the concept of the invention. The samereference numbers will be used throughout this specification to refer tothe same or like parts.

In the following description, the term terminal generically refers to amobile or fixed user terminal device such as a User Equipment (UE), aMobile Station (MS), or an Advanced Mobile Station (AMS). In addition,the term Base Station (BS) generically refers to any node at a networkend which communicates with a UE, such as a Node B, an evolved Node B(eNode B), an Access Point (AP), an Advanced BS (ABS), etc. Thefollowing description is given on the assumption that a UE is an AMSconforming to the IEEE 802.16m standard and a BS is also an ABSconforming to the IEEE 802.16m standard.

In a wireless communication system, a UE can receive information from aBS on a downlink and transmit data to the BS on an uplink. Informationtransmitted from or received at the UE includes data and various typesof control information. There are many physical channels depending onthe types and usages of information transmitted from or received at UEs.

A terminal that conducts Machine to Machine (M2M) communication may bereferred to as various names such as an M2M device, an M2M communicationterminal, and a Machine Type Communication (MTC) terminal. Legacyterminals may be referred to as Human Type Communication (HTC) terminalsor Human to Human (HTH) terminals.

As the number of machine application types increases, M2M devices willalso be gradually increased in number. Machine application types underconsideration are (1) security; (2) public safety; (3) tracking andtracing; (4) payment; (5) healthcare; (6) remote maintenance andcontrol; (7) metering; (8) consumer devices; (9) fleet management inPoint Of Sales (POS)-related and security-related application markets;(10) communication between terminals at a vending machine; (11) remotecontrol of machines and facilities and smart metering for automaticallymeasuring the operation time of construction machines and facilities andheat or power consumption; and (12) surveillance video communication,which should not be construed as limiting the present invention.Besides, many other machine application types are being discussed. Asmachine application types get diversified in this manner, the number ofM2M devices is increasing, compared to the number of legacy terminals,that is, H2H terminals.

The existence of numerous M2M devices within the service area of thesame BS may cause connection congestions between the M2M devices and thelegacy terminals, i.e. H2H terminals and connection collisions betweenthe M2M devices. Accordingly, there exists a need for discussing howefficiently to distribute limited resources to a newly emerged hugenumber of M2M devices in a manner that minimizes effects on the legacyterminals (H2H terminals).

FIG. 1 illustrates a Time Division Duplexing (TDD) frame in anOrthogonal Frequency Division Multiple Access (OFDMA) physical layer.

Referring to FIG. 1, an IEEE 802.16e frame includes a DownLink (DL) zoneand an UpLink (UL) zone. To prevent collision between DL transmissionand UL transmission, a Transmit/receive Transition Gap (TTG) isinterposed between the DL zone and the UL zone and a Receive/transmitTransition Gap (RTG) is inserted at the end of the frame. The firstOrthogonal Frequency Division Multiplexing (OFDM) symbol, of the DL zoneis allocated to a preamble for frame synchronization and cellidentification. The first four subchannels in the second OFDM symbolinclude a Frame Control Header (FCH) that provides MAP configurationinformation. The following subchannels in the second OFDM symbol form aDL-MAP area carrying DL-MAP Information Elements (IEs). A first DL burst(DL burst #1) carries UL-MAP IEs. A ranging subchannel resides in the ULzone. DL bursts and UL bursts carry user data.

FIG. 2 illustrates a data region for defining OFDMA resource allocation.Referring to FIG. 2, a slot allocated to each UE is defined by atwo-dimensional data region which is a set of contiguous subchannelsallocated by a burst. Namely, one data region in OFDMA may berepresented as a rectangle determined by a time coordinate and asubchannel coordinate, as illustrated in FIG. 2.

A data region may be allocated to a specific UE, for UL transmission orDL transmission. To define the data region two-dimensionally, the numberof OFDM symbols in the time domain and the number of contiguoussubchannels starting from a position apart from a reference point by anoffset should be determined.

FIG. 3 illustrates an OFDMA data region in the UL zone of a frame. Inthe IEEE 802.16e system, a UL OFDMA slot is defined as a square area ofone subchannel by three Orthogonal Frequency Division Multiplexing(OFDM) symbols. UL data is divided by the size of one OFDMA slot and theOFDMA slots are sequentially mapped to an OFDMA data region, startingfrom the lowest-numbered subchannel.

FIG. 4 is a flowchart illustrating an initialization procedure of a UE.Referring to FIG. 4, when the UE is powered on, the UE scans for a DLchannel, acquires UL/DL synchronization to a BS, and acquires UL/DLchannel parameters by receiving a DL-MAP IE, a UL-MAP IE, a DownlinkChannel Descriptor (DCD) message, and an Uplink Channel Descriptor (UCD)message (S410).

The UE adjusts UL transmission parameters through ranging with the BSand is allocated a basic management Connection Identifier (CID) and aprimary management CID by the BS (S420). Then the UE performs a basiccapabilities negotiation with the BS (S430) and is authenticated (S440).When the UE is managed by an Internet Protocol (IP) through registrationto the BS, it is allocated a secondary management CID by the BS (S450).The UE establishes an IP connection (S460) and sets a current date andtime (S470). The UE downloads a configuration file from a Trivial FileTransfer Protocol (TFTP) server (S480) and establishes a connection to aprepared service (S490) using the configuration file.

As illustrated in FIG. 4, the process of adjusting transmissionparameters (a frequency offset, a time offset, and transmission power)for UL communication with a BS at a UE during initial networkregistration is called ranging. To maintain UL communication with the BSafter the network registration, the UE performs periodic ranging.

FIG. 5 is a diagram illustrating a signal flow for a ranging procedure.Referring to FIG. 5, the UE acquires DL synchronization (S510) andreceives a UCD message including an initial ranging code (S520). The BSalso transmits a UL-MAP IE including information about a ranging regionand a broadcast CID to the UE (S530). After randomly selecting a rangingslot in the ranging region indicated by the UL-MAP IE, the UE selects aranging code randomly from among ranging codes indicated by the UCDmessage (S540). The UE then transmits the selected ranging code in theselected ranging slot to the BS (S550). Upon receipt of the rangingcode, the BS allocates resources to the UE and transmits a RangingResponse (RNG-RSP) message including values corresponding to thereceived ranging code and slot to the UE (S560).

Now a description will be given of messages/IEs described before withreference to FIGS. 1 to 5. It is clarified that the followingdescription focuses on fields included in each message/IE, related tothe embodiments of the present invention.

Table 1 illustrates an exemplary DL-MAP message.

TABLE 1 Size Syntax (bit) Notes DL-MAP_Message_Format( ) { — — Management Message Type = 2 8 —  PHY Synchronization Field variable Seeappropriate PHY specification.  DCD Count 8 —  Base Station ID 48  — Begin PHY-specific section { — See applicable PHY subclause.   if(WirelessMAN-OFDMA) { — —    No. OFDMA symbols 8 For TDD, the number ofOFDMA symbols in the DL subframe including all AAS/permutation zone andincluding the preamble. For FDD, see 8.4.4.2.2.   } — —   for (i = 1; i<= n; i++) { — For each DL-MAP element 1 to n.    DL-MAP_IE( ) variableSee corresponding PHY specification.   } — —  } — —  if !(byte boundary){ — —   Padding Nibble 4 Padding to reach byte boundary.  } — — } — —

The DL-MAP message defines the usage of each burst allocated to the DLzone in a burst-mode physical layer.

Table 2 illustrates an exemplary UL-MAP message.

TABLE 2 Size Syntax (bit) Notes UL-MAP_Message_Format( ) { — — Management Message Type = 3 8 —  FDD Partition Change Flag 1 For FDDonly. Indicates the next possible partition change. 0b0: Possiblepartition change in next frame 0b1: Minimum number of frames (excludingcurrent frame) before next possible change is given by TLV ‘FDD framepartition change timer’  Reserved 7 Shall be set to zero.  UCD Count 8 — Allocation Start Time 32  —  Begin PHY-specific section { — Seeapplicable PHY subclause.   if (WirelessMAN-OFDMA) { — —    No. OFDMAsymbols 8 For TDD, the number of OFDMA symbols in the UL subframe ForFDD, see 8.4.4.2.2   } — —   for (i = 1; i <= n; i++) { — For eachUL-MAP element 1 to n.    UL-MAP_IE( ) variable See corresponding PHYspecification.   } — —  } — —  if !(byte boundary) { — —   PaddingNibble 4 Padding to reach byte boundary.  } — — } — —

The UL-MAP message defines the usage of each burst allocated to the ULzone.

The usage of a UL-MAP IE is determined by an Uplink Interval Usage Code(UIUC) per CID and the time interval of the UL-MAP IE is indicated by a‘duration’ field. That is, the usage of each UL-MAP IE is determined byUIUC value and the time interval of the UL-MAP IE starts at a positionapart from the previous UL-MAP IE by a duration set in the ‘duration’field.

Table 3 illustrates an exemplary DL-MAP IE.

TABLE 3 Size Syntax (bit) Notes DL-MAP_IE( ) { — —  DIUC 4 —  if (DIUC== 14) { — —   Extended-2 DIUC dependent IE — —  } Else if (DIUC == 15){ — —   Extended DIUC dependent IE variable See 8.4.5.3.2 and8.4.5.3.2.1  } else { — —  . . .  OFDMA Symbol offset 8 —  if(Permutation = 0b11 and — —  (AMC type is 2×3 or 1×6)) {    Subchanneloffset 8 —    Boosting 3 000: Normal (not boosted); 001: +6 dB; 010: −6dB; 011: +9 dB; 100: +3 dB; 101: −3 dB; 110: −9 dB; 111: −12 dB;    No.OFDMA triple symbol 5 Number of OFDMA symbols is given in multiples of 3symbols    No. Subchannels 6 —   } else { — —    Subchannel offset 6 —   Boosting 3 000: Normal (not boosted); 001: +6 dB; 010: −6 dB; 011: +9dB; 100: +3 dB; 101: −3 dB; 110: −9 dB; 111: −12 dB;    No. OFDMASymbols 7 —    No. Subchannels 6 —   } — —   Repetition CodingIndication 2 0b00: No repetition coding 0b01: Repetition coding of 2used 0b10: Repetition coding of 4 used 0b11: Repetition coding of 6 used } — — } — —

Referring to Table 3, a DL-MAP IE specifies a DL traffic area for a UEby a Downlink Interval Usage Code (DIUC), a CID, and burst positioninformation such as a subchannel offset, a symbol offset, the number ofsubchannels, and the number of symbols.

FIG. 4 illustrates an exemplary UL-MAP IE.

TABLE 4 Size Syntax (bit) Notes UL-MAP_IE( ) { — —  CID 16  —  UIUC 4 — if (UIUC == 11) { — —   Extended UIUC 2 dependent IE variable See8.4.5.4.4.2  } — —  else if (UIUC == 12) { — —   OFDMA Symbol offset 8 —  Subchannel offset 7 —   No. OFDMA Symbols 7 —   No. Subchannels 7 —  Ranging Method 2 0b00: Initial ranging/Handover Ranging over twosymbols 0b01: Initial ranging/Handover Ranging over four symbols 0b10:BR/periodic ranging over one symbol 0b11: BR/periodic ranging over threesymbols   Dedicated ranging indicator 1 0: The OFDMA region and rangingmethod defined are used for the purpose of normal ranging 1: The OFDMAregion and ranging method defined are used for the purpose of rangingusing dedicated CDMA code and transmission opportunities assigned in theMOB_PAG-ADV message, in the RNG-RSP message, or in the MOB_SCN- RSPmessage.  . . .   Duration 10  In OFDMA slots (see 8.4.3.1).  . . .

A UL-MAP IE with UIUC=12 allocates a UL region for at least one of theusages of initial ranging, handover ranging, periodic ranging, andbandwidth request ranging, in a contention-based manner.

In OFDMA, a UE performs at least one of a ranging request for adjustingUL transmission parameters and a UL bandwidth request, using a CodeDivision Multiple Access (CDMA) code. In other words, a BS broadcasts aCDMA code set for one of a ranging request and a UL bandwidth request toUEs by a UCD message. Then the UE randomly selects a ranging code fromthe CDMA code set according to an intended usage and transmits theselected ranging code in a UL region allocated for ranging.

Both the DCD and UCD are Medium Access Control (MAC) management messagesincluding DL and UL channel parameters, transmitted by the BS. The BStransmits the DCD and UCD to UEs within its service area everypredetermined time interval.

The UEs acquire information about a coding and modulation scheme usedfor each burst from the DCD/UCD message and encode/decode data based onthe acquired information. In addition, the UEs determine from theDCD/UCD message whether channel parameters of the BS have been changedand update the channel parameters according to the determination.Meanwhile, the UCD message includes information about a back-off timeused to avoid code collision after a CDMA code set and a code related toone of a ranging request and a bandwidth request are transmitted.

The BS allocates a ranging region to UEs in a contention-based manner bya UL-MAP IE. The ranging region may be divided into regions for one ormore of initial ranging, handover ranging, periodic ranging, andbandwidth ranging, according to ranging usages.

Meanwhile, an M2M device may perform M2M ranging pursuant to IEEE802.16e ranging. Notably, a Type/Length/Value (TLV) for M2Mcommunication is defined for an IE or a UCD, when needed. Especially, anM2M ranging region may be indicated by an M2M Ranging Allocation UL-MAPextended IE. The M2M Ranging Allocation UL-MAP extended IE may bedefined as illustrated in Table 5.

TABLE 5 Syntax Size (bit) Notes  Extended UIUC 4 M2M Ranging AllocationUL- MAP Extended = 0xC  Length 4 Length is TBD Access restrictionindicator 1 When this bit is set to 1, it indicates that M2M devices arenot allowed to access this BS. When this bit is set to 0, this IEspecifies the ranging allocation for M2M devices. If (Access restrictionindicator == 0) {  OFDMA Symbol offset 8 —  Subchannel offset 7 —  No.OFDMA Symbols 7 —  No. Subchannels 7 — Ranging Method 2 0b00: Initialranging/Handover Ranging over two symbols 0b01: Initial ranging/HandoverRanging over four symbols 0b10-0b11: Reserved Dedicated rangingindicator 1 0: The OFDMA region and ranging method defined are used forthe purpose of normal ranging 1: The OFDMA region and ranging methoddefined are used for the purpose of ranging using dedicated CDMA codeand transmission opportunities assigned in the MOB PAG-ADV message } }

In Table 5, Extended UIUC is set to 0xC indicating that a regionindicated by the M2M Ranging Allocated UL-MAP extended IE is used inrelation to an M2M dedicated ranging channel. Access restrictionindicator indicates whether M2M devices can access the BS. OFDMA Symboloffset indicates the starting OFDMA symbol, Subchannel offset indicatesthe starting subchannel, No. OFDMA Symbols indicates the number of OFDMAsymbols, and No. Subchannels indicates the number of subchannels.Therefore, the M2M ranging region may be indicated by the OFDMA Symboloffset, Subchannel offset, No. OFDMA Symbols, and No. Subchannels.Dedicated ranging indicator indicates whether the ranging regionindicated by the above-described four fields and a defined rangingmethod are used for normal ranging or M2M dedicated ranging.

If an M2M ranging region is indicated by an M2M Ranging AllocationUL-MAP extended IE as illustrated in Table 5, the obscurity problem mayoccur to the relationship between M2M devices and legacy terminals thatdo not know the M2M Ranging Allocation UL-MAP extended IE. This will bedescribed in detail with reference to FIG. 6.

FIG. 6 illustrates exemplary allocation of an M2M ranging region.According to the IEEE 802.16e standard, OFDMA UL-MAP IEs use blockallocations as UL bandwidth allocations for fast feedback (UIUC=0),Hybrid Automatic Repeat reQuest (HARQ) ACKnowledgment (ACK) CHannel (CH)region (UIUC=11), CDMA ranging and bandwidth request allocation(UIUC=12), and Peak to Average Power Ratio (PAPR)/safety zone allocation(UIUC=13), and slot allocations for all other UL bandwidth allocations.These signals are allocated to the UL zone, above all other signals.Therefore, a ranging region indicated by an M2M Ranging AllocationUL-MAP extended IE 610 in the UL-MAP area of the DL zone may beallocated in the form of a block 620 in a specific region of the ULzone, as illustrated in FIG. 6. However, the M2M ranging region 620 ismerely exemplary and thus various block positions and sizes may be setby OFDMA Symbol offset, Subchannel offset, No. OFDMA Symbols, and No.Subchannels.

Upon receipt of the M2M Ranging Allocation UL-MAP extended IE 610 in theUL-MAP area of the DL zone, a legacy terminal neglects the M2M RangingAllocation UL-MAP extended IE 610 because it does not know the extendedUIUC (=0xC) included in the M2M Ranging Allocation UL-MAP extended IE610. As a result, the legacy terminal may not determine the position andsize of an M2M ranging region in the UL zone, indicated by the M2MRanging Allocation UL-MAP extended IE 610. Moreover, without knowledgeof the length of the M2M ranging region, the legacy terminal has aproblem with using slots following the M2M ranging region in the ULzone. Due to this problem, the BS also has difficulty in efficientlyallocating resources when allocating an M2M ranging region by the M2MRanging Allocation UL-MAP extended IE 610.

To solve the above problem, it is proposed that when an M2M rangingregion is allocated by the M2M Ranging Allocation UL-MAP extended IE610, a conventional OFDMA UL-MAP IE is set also to indicate (identify)the same ranging region as the M2M ranging region. Specifically, theOFDMA UL-MAP IE is set to indicate the same ranging region as the M2Mranging region by the OFDMA Symbol offset, Subchannel offset, No. OFDMASymbols, and No. Subchannel fields. The UIUC is set to 12 to indicateranging and the Dedicated ranging indicator is set to 1 to indicatededicated ranging. This will be described below in detail with referenceto FIG. 7.

FIG. 7 illustrates allocation of an M2M ranging region according to anembodiment of the present invention. Referring to FIG. 7, an OFDMAUL-MAP IE 710 and an M2M Ranging Allocation UL-MAP extended IE 720 aredefined in the DL MAP area of the DL zone and an M2M ranging region 730indicated by both the OFDMA UL-MAP IE 710 and the M2M Ranging AllocationUL-MAP extended IE 72 is defined in the UL zone. As noted from FIG. 7,the OFDMA UL-MAP IE 710 and the M2M Ranging Allocation UL-MAP extendedIE 720 indicate the same region (i.e. the M2M ranging region 730) in theUL zone.

In this case, an M2M device may determine the M2M ranging region by theM2M Ranging Allocation UL-MAP extended IE 720 and thus may performranging in the M2M ranging region. On the other hand, a legacy terminalneglects the M2M Ranging Allocation UL-MAP extended IE 720 because itdoes not know the meaning of the extended UIUC included in the M2MRanging Allocation UL-MAP extended IE 720. However, the legacy terminalmay recognize the presence of a specific ranging region (e.g. theposition, size, etc. of the specific ranging region) by the OFDMA UL-MAPIE 710 indicating the same region as the M2M ranging region.

The legacy terminal may be aware from UIUC=12 that this ranging regionis related to ranging and may determine from dedicated rangingindicator=1 that the ranging region is a dedicated ranging region.Notably, since the OFDMA UL-MAP IE 710 is not intended to allocate adedicated ranging region to the legacy terminal, the BS does nottransmit another MAC management message related to dedicated ranging(e.g. a paging message specifying a dedicated ranging code and atransmission opportunity).

Therefore, the legacy terminal is not capable of using the rangingregion indicated by the OFDMA UL-MAP IE 710, for dedicated ranging.Nonetheless, the legacy terminal may know the same ranging region as theM2M ranging region, indicated by the OFDMA UL-MAP IE 710 and thus noproblem occurs with the legacy terminal's recognition and use of thefollowing regions. If the BS does not include dedicated raginginformation in a paging message, the legacy terminal may be supposed toneglect ranging region information set in the OFDMA UL-MAP IE. Inaddition, the BS may include in a UCD message an indicator indicatingwhether an M2M device can use the ranging region information set in theOFDMA UL-MAP IE.

In summary, when information about an M2M ranging region is transmittedin an M2M Ranging Allocation UL-MAP extended IE, an OFDMA UL-MAP IE withUIUC=12 and dedicated ranging indicator=1 is transmitted to indicate thesame ranging region as the M2M ranging region so as to actively supportranging of M2M devices, while protecting legacy terminals.

The UCD may also face the afore-described problem related to legacyterminals, caused by transmission of the M2M Ranging Allocation UL-MAPextended IE. To solve the problem, when an M2M ranging region TLV istransmitted in the UCD, a ranging region TLV indicating (identifying)the same region as an M2M ranging region may be allocated, which will bedescribed below in great detail. M2M ranging region information may beindicated by OFDMA symbol offset, Subchannel offset, No. OFDMA Symbols,and No. Subchannels in the M2M ranging region TLV of Table 6illustrating a part of the UCD.

TABLE 6 Type Name (1 byte) Length Value Uplink_Burst_Profile 1 Mayappear more than once (see 6.3.2.3.3). The length is the number of bytesin the overall object, including embedded TLV items. Contention-based 21 Number of UL-MAPs to receive before contention-based reservationtimeout reservation is attempted again for the same connection.Frequency 5 4 UL center frequency (kHz). HO_ranging_start^(a) 7 1Initial backoff window size for MS performing initial ranging during HOprocess, expressed as a power of 2. Range: 0-15 (the highest order bitsshall be unused and set to 0). Available UL Radio 24 1 Indicates theaverage ratio of non-assigned UL radio resources to Resources the totalusable UL radio resources. The average ratio shall be calculated over atime interval defined by the UL_radio_resources_window_size parameter(Table 342). The reported average ratio will serve as a relative loadindicator. This value can be biased by the operator provided it reflectsa consistent representation of the average loading condition of BSsacross the operator network. 0x00: 0% 0x01: 1% . . . 0x64: 100%0x65-0xFE: reserved, 0xFF indicates no information available M2M RangingRegion 31 6/12 The value of TLV consists of up to two concatenatedsections (one section per Ranging method), each having the followingstructure: Bit 0: dedicated ranging indicator. indicating an M2M rangingregion allocated for M2M devices only Bits 1-2: ranging method Bits 3-9:num subchannels Bits 10-16: num OFDMA symbols Bits 17-23: subchanneloffset Bits 24-31: OFDMA symbol offset Bits 32-34: Parameter d thatdefines periodicity of 2^(d) frames Bits 35-39: Allocation phaseexpressed in frames. 0 ≦ Allocation Phase < periodicity(= 2^(d)) Bits40-47: Reserved

In this case, Ranging Region is set to indicate the same region as M2MRanging Region in Table 7 illustrating a part of a UCD with TLV=212.

TABLE 7 Type Name (1 byte) Length Value . . . Ranging Region 2125/10/15/ The value of TLV consists of up to four concatenated sections20 (one section per Ranging method), each having the followingstructure: Bit 0: dedicated ranging indicator Bits 1-2: ranging methodBits 3-9: num subchannels Bits 10-16: num OFDMA. symbols. Bits 17-23:subchannel offset Bits 24-31: OFDMA symbol offset Bits 32-34, Parameterd that defines periodicity of 2^(d) frames Bits 35-39, Allocation phaseexpressed in frames, 0 ≦ Allocation Phase < periodicity (=2^(d)) . . .

Referring to Table 7, among values that define a ranging region, OFDMAsymbol offset, Subchannel offset, No. OFDMA Symbols, and No. Subchannelsare set to the same values as those of the fields of TLV 31. That is,TLV 31 and TLV 212 in a UCD 810 are set to indicate the same rangingregion 820, as illustrated in FIG. 8. In TLV 212, the dedicated rangingindicator is set to 1. In this manner, ranging of M2M devices can beactively supported, while protecting legacy terminals, based on the sameprinciple of the case of using the M2M Ranging Allocation UL-MAPextended IE.

FIG. 9 is a block diagram of an M2M device and a BS according to anembodiment of the present invention.

Referring to FIG. 9, an M2M device 900 and a BS 950 may include RadioFrequency (RF) units 910 and 960, processors 920 and 970, and memories930 and 980, respectively. Each RF unit 910 or 960 may include atransmitter 911 or 961 and a receiver 912 or 962.

The transmitter 911 and the receiver 912 of the M2M device 900 areconfigured so as to transmit signals to and receive signals from the BS950 and another M2M device. The processor 920 is functionally connectedto the transmitter 911 and the receiver 912 to control signaltransmission and reception to and from other terminals through thetransmitter 911 and the receiver 912.

The processor 920 processes a transmission signal and then transmits theprocessed signal to the transmitter 911. The processor 920 alsoprocesses a signal received from the receiver 912. When needed, theprocessor 920 may store information included in exchanged messages inthe memory 930. The M2M device 900 having the above-describedconfiguration may implement the methods according to the foregoingembodiments of the present invention.

While not shown in FIG. 9, the M2M device 900 may further include manyother components according to its application type. If the M2M device900 is designed for smart metering, it may further include a componentfor power measuring. The power measuring operation may be performedunder the control of the processor 920 or a separately procuredprocessor (not shown).

While communication is conducted between the M2M device 900 and the BS950 in the illustrated case of FIG. 9, M2M communication may also beperformed between M2M devices according to the present invention. Eachterminal having the same configuration illustrated in FIG. 9 may performthe methods according to the foregoing embodiments of the presentinvention.

Meanwhile, the transmitter 961 and the receiver 962 of the BS 950 areconfigured to transmit signals to and receive signals from another BS,an M2M server, and M2M devices. The processor 970 is functionallyconnected to the transmitter 961 and the receiver 962 to thereby controlsignal transmission and reception to and from other terminals throughthe transmitter 961 and the receiver 962.

The processor 970 processes a transmission signal and then transmits theprocessed signal to the transmitter 961. The processor 970 alsoprocesses a signal received from the receiver 962. When needed, theprocessor 970 may store information included in an exchanged message inthe memory 980. The BS 950 having this configuration may perform themethods according to the foregoing embodiments of the present invention.

The processors 920 and 970 of the M2M device 900 and the BS 950 command(e.g. control, adjust, and manage) operations of the M2M device 900 andthe BS 950, respectively. The processors 920 and 970 may be connectedrespectively to the memories 930 and 980 that store program codes anddata.

The memories 930 and 980 are connected to the processors 920 and 970 andstore an Operating System (OS), applications, and general files.

The processors 920 and 970 may also be called controllers,microcontrollers, microprocessors, or microcomputers. Meanwhile, theprocessors 920 and 970 may be implemented by various means, for example,hardware, firmware, software, or a combination thereof. In a hardwareconfiguration, the processors 920 and 970 may include one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSDPs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), etc. which are configured to implement the present invention.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. Firmware or software configured to implement the presentinvention may be included in the processors 920 and 970, or may bestored in the memories 930 and 980 and executed by the processors 920and 970.

MODE FOR INVENTION

Various embodiments have been described in the best mode for carryingout the invention.

INDUSTRIAL APPLICABILITY

The network reentry methods of an M2M device are applicable to variouswireless communication systems including 3^(rd) Generation PartnershipProject (3GPP) Long Term Evolution-Advanced (LTE-A) and IEEE 802.

The embodiments of the present invention described above arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It is obvious tothose skilled in the art that claims that are not explicitly cited ineach other in the appended claims may be presented in combination as anexemplary embodiment of the present invention or included as a new claimby a subsequent amendment after the application is filed.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

The invention claimed is:
 1. A method for transmitting Machine toMachine (M2M) ranging information at a Base Station (BS) in a wirelesscommunication system, the method comprising: transmitting an UplinkChannel Descriptor (UCD) including both a ranging region fieldconfigured with a first type of configuration for ranging of a non-M2Mdevice and a M2M ranging region field configured with a second type ofconfiguration for ranging of a M2M device, the M2M ranging region fieldindicating a M2M ranging region and the ranging region field for thenon-M2M device identifying the same M2M ranging region as the M2Mranging region field for the M2M device in the UCD; receiving a rangingcode from the M2M device in the M2M ranging region; and transmittingranging information via a paging message to the M2M device, wherein theranging region field is neglected by the non-M2M device, the basestation does not receive a ranging code from the non-M2M device in theranging region, and the ranging information in the paging message is nottransmitted to the non-M2M device.
 2. The method according to claim 1,wherein a dedicated ranging indicator is set to 1 in the ranging regionfield of the UCD.
 3. The method according to claim 1, wherein the M2Mranging region specified by the M2M ranging region field is indicated byan Orthogonal Frequency Division Multiple Access (OFDMA) symbol offset,a subchannel offset, the number of OFDMA symbols, and the number ofsubchannels.
 4. The method according to claim 1, wherein the M2M rangingregion specified by the ranging region field is indicated by an OFDMAsymbol offset, a subchannel offset, the number of OFDMA symbols, and thenumber of subchannels.
 5. The method according to claim 1, wherein theM2M ranging region specified by the M2M ranging region field is used forthe M2M device to transmit a ranging code.
 6. A method for receivingMachine to Machine (M2M) ranging information at an M2M device in awireless communication system, the method comprising: receiving anUplink Channel Descriptor (UCD) including both a ranging region fieldconfigured with a first type of configuration for ranging of a non-M2Mdevice and a M2M ranging region field configured with a second type ofconfiguration for ranging of the M2M device, the M2M ranging regionfield indicating a M2M ranging region and the ranging region field forthe non-M2M device identifying the same M2M ranging region as the M2Mranging region field for the M2M device, transmitting a ranging code inthe M2M ranging region; and receiving ranging information via a pagingmessage, wherein the ranging region field is neglected by the non-M2Mdevice, the base station does not receive a ranging code from thenon-M2M device in the ranging region, and the ranging information in thepaging message is not transmitted to the non-M2M device.
 7. The methodaccording to claim 6, wherein a dedicated ranging indicator is set to 1in the ranging region field of the UCD.
 8. The method according to claim6, wherein the M2M ranging region specified by the M2M ranging regionfield is indicated by an Orthogonal Frequency Division Multiple Access(OFDMA) symbol offset, a subchannel offset, the number of OFDMA symbols,and the number of subchannels.
 9. The method according to claim 6,wherein the M2M ranging region specified by the ranging region field isindicated by an OFDMA symbol offset, a subchannel offset, the number ofOFDMA symbols, and the number of subchannels.
 10. The method accordingto claim 6, wherein the non-M2M device does not receive the pagingmessage including the ranging information, and the non-M2M deviceneglects the ranging region field.
 11. The method according to claim 6,further comprising transmitting a ranging code using M2M ranging regionfield set by the M2M ranging region field.
 12. A Base Station (BS) fortransmitting Machine to Machine (M2M) ranging information in a wirelesscommunication system, the BS comprising: a Radio Frequency (RF) unit;and a processor that controls the RF unit to: transmit an Uplink ChannelDescriptor (UCD) including both a ranging region field configured with afirst type of configuration for ranging of a non-M2M device and a M2Mranging region field configured with a second type of configuration forranging of a M2M device, the M2M ranging region field indicating a M2Mranging region and the ranging region field for the non-M2M deviceidentifying the same M2M ranging region as the M2M ranging region fieldfor the M2M device in the UCD, receive a ranging code from the M2Mdevice in the M2M ranging region; and transmit ranging information via apaging message to the M2M device, wherein the ranging region field isneglected by the non-M2M device, the base station does not receive aranging code from the non-M2M device in the ranging region, and theranging information in the paging message is not transmitted to thenon-M2M device.
 13. A Machine to Machine (M2M) device for receiving M2Mranging information in a wireless communication system, the M2M devicecomprising: a Radio Frequency (RF) unit; and a processor that controlsthe RF unit to: receive an Uplink Channel Descriptor (UCD) includingboth a ranging region field having a first type of configuration forranging of a non-M2M device and a M2M ranging region field having asecond type of configuration for ranging of the M2M device, the M2Mranging region field indicating a M2M ranging region and the rangingregion field for the non-M2M device identifying the same M2M rangingregion as the M2M ranging region field for the M2M device, transmit aranging code in the ranging region; and receive ranging information viaa paging message, wherein the ranging region field is neglected by thenon-M2M device, the base station does not receive a ranging code fromthe non-M2M device in the ranging region, and the ranging information inthe paging message is not transmitted to the non-M2M device, and thenon-M2M device neglects the ranging region field.